In this work, we consider the same dataset as in [1]}, where a single urban microcell (UMi) with 150 meters radius is considered. The CSI datasets at \(2.5\)  GHz (for UL) and at \(2.62\)  GHz (for DL) are generated with the \(\textsc {Matlab}\)  based software QuaDRiGa version 2.2 [2]}. Specifically, non-line-of-sight (NLoS) channels with \(L=58\)  micropaths are considered.
The bandwidth is approximately 8 MHz and is divided over \(N_{\text{c}} =160\)  subcarriers. The BS is equipped with a uniform planar array with \(N_\text{a} = 8\times 8 =64\)  antennas, whereas the MTs have a single antenna each.
A total of \(60\times 10^3\)  samples of both UL CSI, \(H_{\text{UL}} \in \mathbb {C}^{N_{\text{a}}\times N_{\text{c}}}\) , and DL CSI, \(H_{\text{DL}}\)  are collected. Subsequently, the dataset is split into three subsets of training, validation, and testing, each with \(48\times 10^3\) , \(6\times 10^3\) , and \(6\times 10^3\)  samples, respectively.
As outlined before, for training and codebook design only the samples of \(H_{\text{UL}} \subseteq \text{\lbrace training, validation\rbrace }\)  are used, whereas the performance metrics are evaluated with respect to the samples of \(H_{\text{DL}} \subseteq \text{\lbrace testing\rbrace }\) .
